In the technical field of gas turbines there is a commercial requirement to measure the emissions from gas turbine engines in order to comply with national and regional environmental standards. In particular, there is a need to measure lube oil breather emissions from a gas turbine. The lube oil breather emission flows through a breather pipe in a liquid (droplet) and/or a gaseous aggregate state. The lube oil breather pipe comprises a relatively small diameter and the flow of the lube oil (mist) is relatively low and comprises high temperatures.
Hence, in order to receive a proper measurement result, a measurement sample has to be taken from the oil mist inside breather pipe. In particular, the hydrocarbon amount of the oil mist in the gaseous phase and in the liquid phase is measured, so that a total amount of hydrocarbon of the oil mist and hence the lube oil breather emissions is analysed.
GB 2 408 798 A discloses a light scattering oil mist detecting device with means for preventing oil droplets entering the casing. The oil mist detecting device comprises a casing having an oil mist introducing chamber arranged in a crank-case of on internal combustion engine. A light emitting means and a photo detecting means of the oil mist detecting device may measure the oil mist introduced into the introducing chamber.
GB 2 398 382 A discloses an oil mist sampling device. The oil mist sampling device comprises light emitting means for radiating light and photo receiving means for receiving the radiated light. The photo receiving means outputs a signal corresponding to the intensity of the received light.
U.S. Pat. No. 6,369,890 B1 discloses a particle separation and detection apparatus. The apparatus comprises an analysing chamber which receives a gaseous fluid by diffusion from a receiving chamber connected via an inlet to an area being monitored. The gaseous fluid is measured by a photodiode which detects light scattered by particles in the gaseous fluid.
EP 1 936 358 A1 discloses an oil mist detector. A light emit-ting device irradiates light to a detection region in which oil mist is injected. The light is radiated through a transparent window. The received light is received through the transparent window by a receiving device.
Liquid emissions may be caught on a fiber packed filter assembly with a backup membrane filter. A conventional method of determining the liquid oil catch is weighting before and after exposure but this may be prone to possible errors. The more accurate method may be to extract the liquid oil catch from an exhausted oil mist by using a solvent and then analyzing the concentration of the liquid oil catch (e.g. its hydrocarbons) in the solvent.